A typical cellular wireless network includes a number of base stations each radiating to define a respective coverage area in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, could operate. In particular, each coverage area may operate on one or more carriers each defining a respective frequency bandwidth of coverage. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
Further, a cellular wireless network may operate in accordance with a particular air interface protocol (radio access technology), with communications from the base stations to UEs defining a downlink or forward link and communications from the UEs to the base stations defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Long Term Evolution (LTE) (using Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), Global System for Mobile Communications (GSM), IEEE 802.11 (WIFI), and BLUETOOTH, among others. Each protocol may define its own procedures for registration of UEs, initiation of communications, handover between coverage areas, and other functions related to air interface communication.
When a UE enters into coverage of a base station, the UE and base station could engage in signaling with each other to establish a radio-link layer connection through which the base station and UE could exchange bearer data. In that state, the UE is considered to be in a “connected” (or “active”) mode, in which the UE could transmit bearer data to the base station and the base station could transmit bearer data to the UE. Further, once there has been a threshold period of no communication flowing over the UE's radio-link layer connection, the base station may release the UE's radio-link layer connection, transitioning the UE to an “idle” (or “dormant”) mode. In the idle mode, the UE may periodically check for page messages from the base station and, if the UE detects a page message or otherwise seeks to engage in bearer communication, the UE could then engage in signaling with the base station to transition back to the connected mode. And this process may then repeat, with the UE operating in the connected mode and then transitioning to the idle mode and so forth.